1. Field of the Invention
The present invention relates to tunable optical filters and re-configurable optical channel dropping de-multiplexers utilized in optical communications systems. More particularly, the present invention relates to a tunable filter and re-configurable optical channel dropping de-multiplexer wherein a selected wavelength channel from among a plurality of channels comprising a wavelength division multiplexed composite optical signal is delivered to a desired port.
2. Description of the Related Art
Optical fibers are used extensively in telecommunications systems. It is often necessary to add or drop a wavelength channel in optical links or systems. Channel dropping can be achieved by a tunable filter or a re-configurable channel dropping de-multiplexer. Such a tunable filter or re-configurable de-multiplexer receives, from an input port, a wavelength division multiplexed composite optical signal that comprises several channels, or “wavelengths”. These plural channels may include one or more “dropped channels” or wavelengths that a user wishes to remove, or “drop” to selected local channel drop ports, and, optionally, other “express” channels that the user wishes to send, as a wavelength division multiplexed composite optical signal, to another destination.